The city has more than 500 historical monuments, which can be explored easily by foot. Albrecht of Saxony built a castle in Harlingen in 1500, to repress the locals and to provide for his armies. A low earthen city wall with surrounding canal was built to defend the town. During the freedom war of the Dutch against the Spanish, Adriaan Antonisz was ordered to turn the city into a fortress. A new canal accompanied by a high wall was built, including so-called dwingers, some kind of spiked defensive pieces. A lot of these have been removed in the 19th century, but the leftovers are still visible.

Harlingen is the basis for traditional clippers and other old vessels bringing their company to the islands in the Waddenzee, to trips on the IJsselmeer and to the many Frisian lakes en waters. Well-known author Simon Vestdijk was born in Harlingen and refers to his native city regularly in his books.